How caffeine actually gets into a cup of tea

Every LyfeScoop product page lists caffeine per prepared serving. It is a useful number, and an honest one, but it is worth understanding what it describes: the result of a process that happens in your kettle and your cup, not a fixed quantity poured from the tin.

Caffeine lives in the leaf

Tea leaves — black, green, oolong and white all come from the same plant, Camellia sinensis — contain caffeine as part of the plant’s own chemistry. Herbal blends made from chamomile, mint, ginger or lemon balm do not contain tea leaves, which is why they are caffeine-free. The amount in the dry leaf varies with the cultivar, the part of the plant picked and how it was processed.

Extraction does the rest

When hot water meets leaf, caffeine dissolves into the water. Four things control how much ends up in the cup:

• Leaf quantity. More leaf per ounce of water means more caffeine. A heaping teaspoon and a level teaspoon are different cups.
• Water temperature. Hotter water extracts faster. A black tea at 205°F gives up more caffeine in four minutes than a green tea at 175°F in three.
• Steep time. Caffeine extracts relatively early in the steep, but it keeps coming. Leave the leaves in twice as long and you get a stronger cup in every sense.
• Re-steeping. A second steep of the same leaves gives less caffeine than the first, which is one reason a re-steep in the afternoon can feel like a gentler cup.

Why “approximately” is the honest word

Because all four variables are in your hands, a per-serving figure can only describe a specific preparation — the one printed on the product page. Follow those instructions and you will land near the number. Brew double-strength to pour over ice and you will be above it. Cold-brew overnight and you may be below it. That is not a flaw in the tea; it is how tea works.

For reference, caffeine levels in brewed coffee vary significantly by bean, serving size and preparation method, so a cup-for-cup comparison is only meaningful when both cups are specified.

What we do about it

We list caffeine per prepared serving using the preparation on the product page, we say “approximately”, and we tell you what changes it. If you are managing your total daily caffeine intake, the label is the starting point and your kettle is the rest of the equation.